title: Evaluation of passage of fetal erythrocytes into maternal circulation after invasive obstetric procedures.
abstract: OBJECTIVE
  The aim of this study was to evaluate the passage of fetal erythrocytes into the maternal circulation after invasive obstetric procedures, using the Kleihauer-Betke test, flow cytometry and α-fetoprotein concentration in maternal blood.
  
  
  METHODS
  This was a prospective descriptive study on patients who underwent: amniocentesis, cordocentesis, chorionic villus sample, amniotic infusion, bladder drainage and ventricular-amniotic shunt to investigate the karyotype; treatment for hydrocephalus, oligohydramnios, obstructive uropathy and polyhydramnios; and investigation of lung maturity. Maternal blood samples were collected before and 60 min after the invasive obstetric procedure in order to evaluate the passage of fetal erythrocytes using the Kleihauer-Betke test, flow cytometry and α-fetoprotein concentration.
  
  
  RESULTS
  In total, 43 invasive obstetric procedures were performed. The procedures performed were: 27 cases of amniocentesis (62.7%), seven cases of cordocentesis (16.2%), four chorionic villus samples (9.4%), two amniotic infusions (4.7%), two ventricular-amniotic shunts and one bladder drainage (2.3%). After one case of cordocentesis with two puncture attempts via the placenta, a significant increase in fetal erythrocytes was detected using the three methods. After another cordocentesis with one puncture via the placenta, a significant increase in fetal erythrocytes was detected using flow cytometry and α-fetoprotein concentration, but not through the Kleihauer-Betke test. The other 41 samples did not show any significant increase in fetal erythrocytes in the maternal blood.
  
  
  CONCLUSIONS
  Invasive obstetric procedures performed during prenatal care are safe when performed by experienced professionals with the proper technique, with minimal chance of passage of fetal erythrocytes into the maternal compartment.
authors.affiliation: Department of Obstetrics, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil.
authors.forename: Daniela
authors.initials: D
authors.lastname: Meleti
authors.forename: Leandro Gustavo
authors.initials: LG
authors.lastname: De Oliveira
authors.forename: Edward
authors.initials: E
authors.lastname: Araujo Júnior
authors.forename: Ana Carolina Rabachini
authors.initials: AC
authors.lastname: Caetano
authors.forename: Tatiane
authors.initials: T
authors.lastname: Boute
authors.forename: Luciano Marcondes Machado
authors.initials: LM
authors.lastname: Nardozza
authors.forename: Antonio Fernandes
authors.initials: AF
authors.lastname: Moron
mesh_terms: D000293:Adolescent; D000328:Adult; D000649:Amniocentesis / Q000009:adverse effects*; D015193:Chorionic Villi Sampling / Q000009:adverse effects*; D017218:Cordocentesis / Q000009:adverse effects*; D004912:Erythrocytes; D005260:Female; D005315:Fetal Diseases / Q000097:blood / Q000175:diagnosis*; D005331:Fetomaternal Transfusion / Q000097:blood / Q000209:etiology*; D006801:Humans; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood / Q000175:diagnosis*; D011446:Prospective Studies; D055815:Young Adult
keywords: Kleihauer-Betke test; fetomaternal hemorrhage; flow cytometry; invasive obstetric procedures; α-fetoprotein